1. Field of the Invention
The present invention relates generally to a dicing apparatus, a kerf inspecting method and a kerf inspecting system, and more particularly to a dicing apparatus that has two spindles to which blades are attached, a kerf inspecting method and a kerf inspecting system.
2. Description of Related Art
A dicing apparatus cuts a wafer with an outer diameter blade with abrasive grains into the dice. The blade becomes worn, and thus chipping occurs and the center of the blade is displaced from the center of a street (a border line between chips on the wafer) along which the wafer is cut due to heat deformation of the blade. Therefore, the dicing apparatus inspects a groove (a kerf) made by the blade at a predetermined time. The dicing apparatus determines a position and a width of the kerf and whether chipping has occurred by imaging the kerf with a camera and processes the image, or an operator determines them manually by sight.
The dicing apparatus has one spindle to which the blade is attached or two spindles. A twin-spindle dicing saw with two spindles cuts the wafer along two streets at one time or in the step-cut method. In the step-cut method, a first blade cuts the wafer along a street to make a groove with a predetermined depth, and then a second blade cuts the wafer along the groove to cut off the wafer along the street.
Conventionally, the twin-spindle dicing saw inspects kerfs made by the blades as follows. First, the first blade cuts the wafer along a street to make a kerf with the predetermined depth, and the dicing saw inspects the kerf made by the first blade. Then, the second blade cuts the wafer along the kerf made by the first blade to make a kerf, and the dicing saw inspects the kerf made by the second blade.
As described above, the dicing saw cuts the wafer to make the kerfs in the same way as in the cutting operation and inspects the kerfs.
In the conventional kerf inspecting method, however, the groove g made by the second blade is along the same street as the groove G made by the first blade as shown in FIG. 8(a), and thus it is difficult to inspect the kerfs by processing the images. In particular, if the blades are of the same thickness as shown in FIG. 8(b), the groove G1 made by the first blade can not be distinguished from the groove G2 made by the second blade, and thus the kerfs can not be accurately inspected.
In view of the foregoing, it is an object of the present invention to provide a dicing apparatus that can accurately inspect kerfs, a kerf inspecting method and a kerf inspecting system.
To achieve the above-mentioned object, the present invention is directed to a dicing apparatus, comprising: a first blade which cuts a wafer along a street on the wafer to make a groove with a predetermined depth; and a second blade which cuts the wafer along the groove to cut off the wafer along the street, wherein the dicing apparatus sets a time and a position at which each blade makes a kerf for inspecting the kerf.
According to the present invention, the dicing apparatus sets the time and the position at which each blade makes the kerf for inspecting the kerf. Thus, each blade can make the kerf at the most suitable time at the most suitable position.
To achieve the above-mentioned object, the present invention is directed to a kerf inspecting method for a dicing apparatus that comprises a first blade cutting a wafer along a street on the wafer to make a groove with a first predetermined depth and a second blade cutting the wafer along the groove to cut off the wafer along the street, the kerf inspecting method comprising the steps of: cutting, in a state where the wafer has not been cut along a street, the wafer along the street with the second blade to make a kerf with a second predetermined depth; and inspecting the kerf made by the second blade;
According to the present invention, the second blade cuts the wafer along the street along which the first blade has not cut the wafer to make the kerf with the predetermined depth, and then the dicing apparatus inspects the kerf made by the second blade. Therefore, since the kerf is made along the street along which the first blade has not cut the wafer, the kerf made by the second blade is accurately inspected.
Preferably, the second predetermined depth of the kerf made by the second blade is smaller than the first predetermined depth of the groove made by the first blade; and after the kerf is inspected, the first blade cuts the wafer along the kerf made by the second blade to make the groove with the first predetermined depth, and the second blade then cuts the wafer along the groove to cut off the wafer along the street. Thereby, the kerf made by the second blade can be erased by the first blade, and the cutting operation can be resumed without any trouble after the kerf is inspected.
To achieve the above-mentioned object, the present invention is directed to a kerf inspecting method for a dicing apparatus that comprises a first blade cutting a wafer along a street on the wafer to make a groove with a first predetermined depth and a second blade cutting the wafer along the groove to cut off the wafer along the street, the kerf inspecting method comprising the steps of: cutting, in a state where the wafer has not been cut along a first street, the wafer along the first street with the first blade to make a first kerf with a second predetermined depth; cutting, in a state where the wafer has not been cut along a second street, the wafer along the second street with the second blade to make a second kerf with a third predetermined depth; and inspecting the first and second kerfs made by the first blade and the second blade.
According to the present invention, the kerfs are made by the blades along different streets to be inspected. Therefore, the kerfs made by the blades can be accurately inspected.
Preferably, the third predetermined depth of the second kerf made by the second blade is smaller than the first predetermined depth of the groove made by the first blade; and after the second kerf is inspected, the first blade cuts the wafer along the second kerf made by the second blade to make the groove with the first predetermined depth, and the second blade then cuts the wafer along the groove to cut off the wafer along the second street. Thereby, the kerf made by the second blade can be erased by the first blade, and the cutting operation can be resumed without any trouble after the kerf is inspected.
Preferably, the second predetermined depth of the first kerf made by the first blade is equal to the first predetermined depth of the groove made by the first blade. However, the second predetermined depth of the first kerf made by the first blade can be different from the first predetermined depth of the groove made by the first blade.